1. **State the problem:** We have two numbers, one is positive and is 3 times the other. If we add 2 to the larger number and 5 to the smaller number, then one becomes twice the other. We need to find the smaller number.
2. **Define variables:** Let the smaller number be $x$. Then the larger number is $3x$.
3. **Write the condition after adding:** Adding 2 to the larger number gives $3x + 2$, and adding 5 to the smaller number gives $x + 5$.
4. **Set up the equation:** One number becomes twice the other. This gives two possible equations:
a) $3x + 2 = 2(x + 5)$
b) $x + 5 = 2(3x + 2)$
5. **Solve equation (a):**
$$3x + 2 = 2x + 10$$
Subtract $2x$ from both sides:
$$3x - 2x + 2 = 10$$
$$x + 2 = 10$$
Subtract 2:
$$x = 8$$
6. **Check if $x=8$ is valid:**
Smaller number $= 8$ (positive), larger $= 3 \times 8 = 24$.
After adding: larger $= 24 + 2 = 26$, smaller $= 8 + 5 = 13$.
Check if one is twice the other: $26 = 2 \times 13$ is true.
7. **Solve equation (b):**
$$x + 5 = 2(3x + 2)$$
$$x + 5 = 6x + 4$$
Subtract $x$ from both sides:
$$5 = 5x + 4$$
Subtract 4:
$$1 = 5x$$
$$x = \frac{1}{5}$$
8. **Check if $x=\frac{1}{5}$ is valid:**
Smaller number $= \frac{1}{5}$ (positive), larger $= 3 \times \frac{1}{5} = \frac{3}{5}$.
After adding: larger $= \frac{3}{5} + 2 = \frac{3}{5} + \frac{10}{5} = \frac{13}{5}$, smaller $= \frac{1}{5} + 5 = \frac{1}{5} + \frac{25}{5} = \frac{26}{5}$.
Check if one is twice the other: $\frac{26}{5} = 2 \times \frac{13}{5}$ is true.
9. **Conclusion:** Both $x=8$ and $x=\frac{1}{5}$ satisfy the conditions, but since the problem states "a positive number is 3 times another number," both are positive. The smaller number can be either $8$ or $\frac{1}{5}$ depending on which number is considered smaller initially.
Since $x$ is defined as the smaller number, the smaller number is either $8$ or $\frac{1}{5}$. However, $8$ is larger than $\frac{1}{5}$, so the smaller number is $\frac{1}{5}$.
**Final answer:** The smaller number is $\boxed{\frac{1}{5}}$.
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